title: Gonadotropin-releasing hormone neurones innervate kisspeptin neurones in the female mouse brain.
abstract: Kisspeptin (KP) neurones in the rostral periventricular area of the third ventricle (RP3V) and arcuate nucleus (Arc) are important elements in the neuronal circuitry regulating gonadotropin-releasing hormone (GnRH) secretion. KP and co-synthesised neuropeptides/neurotransmitters act directly on GnRH perikarya and processes. GnRH neurones not only form the final output pathway regulating the reproductive functions of the anterior pituitary gland, but also provide neuronal input to sites within the hypothalamus. The current double-label immunohistochemical studies investigated whether GnRH-immunoreactive (IR) projections to the RP3V and/or Arc establish morphological connections with KP-IR neurones at these sites. To optimise visualisation of KP immunoreactivity in, respectively, the RP3V and Arc, ovariectomised (OVX) oestrogen-treated and OVX oil-treated female mice were studied. Confocal laser microscopic analysis of immunofluorescent specimens revealed GnRH-IR axon varicosities in apposition to approximately 25% of the KP-IR neurones in the RP3V and 50% of the KP-IR neurones in the Arc. At the ultrastructural level, GnRH-IR neurones were seen to establish asymmetric synaptic contacts, which usually reflect excitatory neurotransmission, with KP-IR neurones in both the RP3V and Arc. Together with previous data, these findings indicate reciprocal connectivity between both of the KP cell populations and the GnRH neuronal system. The functional significance of the GnRH-IR input to the two separate KP cell populations requires electrophysiological investigation.
authors.affiliation: Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
authors.forename: Imre
authors.initials: I
authors.lastname: Kalló
authors.forename: Barbara
authors.initials: B
authors.lastname: Vida
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Bardóczi
authors.forename: Anett
authors.initials: A
authors.lastname: Szilvásy-Szabó
authors.forename: Fruzsina
authors.initials: F
authors.lastname: Rabi
authors.forename: Tamás
authors.initials: T
authors.lastname: Molnár
authors.forename: Imre
authors.initials: I
authors.lastname: Farkas
authors.forename: Alain
authors.initials: A
authors.lastname: Caraty
authors.forename: Jens
authors.initials: J
authors.lastname: Mikkelsen
authors.forename: Clive W
authors.initials: CW
authors.lastname: Coen
authors.forename: Erik
authors.initials: E
authors.lastname: Hrabovszky
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Liposits
mesh_terms: D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000378:metabolism; D001921:Brain / Q000166:cytology* / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D021621:Imaging, Three-Dimensional; D007150:Immunohistochemistry; D059648:Kisspeptins / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D010052:Ovariectomy; D013569:Synapses / Q000378:metabolism; D020542:Third Ventricle
chemical_list: D004967:Estrogens; D059648:Kisspeptins; D007987:Gonadotropin-Releasing Hormone